| 1. |
- Edsjö, Anders, et al.
(författare)
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Differences in early and late responses between neurotrophin-stimulated trkA- and trkC-transfected SH-SY5Y neuroblastoma cells
- 2001
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Ingår i: Cell Growth & Differentiation. - 1044-9523. ; 12:1, s. 39-50
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Tidskriftsartikel (refereegranskat)abstract
- Despite their sympathetic neuroblast origin, highly malignant neuroblastoma tumors and derived cell lines have no or low expression of the neurotrophin receptor genes, trkA and trkC. Expression of exogenous trkA in neuroblastoma cells restores their ability to differentiate in response to nerve growth factor (NGF). Here we show that stable expression of trkC in SH-SY5Y neuroblastoma cells resulted in morphological and biochemical differentiation upon treatment with neurotrophin-3 (NT-3). To some extent, trkA- and trkC-transfected SH-SY5Y (SH-SY5Y/trkA and SH-SY5Y/trkC) cells resembled one another in terms of early signaling events and neuronal marker gene expression, but important differences were observed. Although induced Erk 1/2 and Akt/PKB phosphorylation was stronger in NT-3-stimulated SH-Y5Y/trkC cells, activation of the immediate-early genes tested was more prominent in NGF-treated SH-SY5Y/ trkA cells. In particular, c-fos was not induced in the SH-SY5Y/trkC cells. There were also phenotypic differences. The concentrations of norepinephrine, the major sympathetic neurotransmitter, and growth cone-located synaptophysin, a neurosecretory granule protein, were increased in NGF-treated SH-SY5Y/trkA but not in NT-3-treated SH-SY5Y/trkC cells. Our data suggest that NT-3/p145trkC and NGF/p140trkA signaling differ in some aspects in neuroblasoma cells, and that this may explain the phenotypic differences seen in the long-term neurotrophin-treated cells.
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| 2. |
- Edsjö, Anders, et al.
(författare)
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Expression of trkB in Human Neuroblastoma in Relation to MYCN Expression and Retinoic Acid Treatment.
- 2003
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Ingår i: Laboratory Investigation. - 1530-0307. ; 83:6, s. 813-823
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Tidskriftsartikel (refereegranskat)abstract
- Expression of full-length trkB can be found in some highly malignant neuroblastoma tumors with an amplified MYCN gene. This contrasts sympathetic neuroblasts, from which neuroblastomas are thought to arise, which neither express trkB nor are dependent on the p145trkB ligands, brain-derived neurotrophic factor (BDNF) or neurotrophin-4/5, for their normal development. In this study we show that trkB was expressed in two out of five neuroblastoma tumors with amplified MYCN, while no trkB expression was observed when the MYCN gene was overexpressed in a non–MYCN-amplified neuroblastoma cell line. This shows that MYCN overexpression per se is not sufficient to induce trkB expression. trkB expression and BDNF responsiveness in neuroblastoma cells can be induced by all-trans-retinoic acid (RA). When SH-SY5Y cells were stimulated with a combination of RA and BDNF, norepinephrine and tyrosine hydroxylase levels were unaltered, showing that the cells did not change toward a more catecholaminergic sympathetic phenotype. However, expression of growth-associated protein 43, indicative of a neuronal phenotype, was elevated. Vesicular acetylcholine transporter, choline acetyl transferase, and neuropeptide tyrosine mRNA levels also increased in RA-BDNF–treated cells, which could suggest that these cells develop into a sympathetic cholinergic phenotype. In addition, treatment with RA-induced expression of the platelet-derived growth factor receptor-alpha. As previously shown for BDNF, platelet-derived growth factor stimulated growth of the RA-treated cells, findings that could have clinical relevance. If these receptors mediate a mitogenic signal in vivo also, this might limit the effect of RA treatment on neuroblastoma patients.
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| 3. |
- Edsjö, Anders
(författare)
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Neuroblastoma Cell Differentiation: The Role of Neurotrophin Receptor Signaling and N-myc Expression
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neuroblastoma is a tumor of sympathetic nervous system derivation, mostly afflicting young children. This thesis is focused on a group of receptor proteins for neurotrophic factors, the Trk family, and on N-Myc, a transcription factor, all important in the formation of the sympathetic nervous system as well as in determining neuroblastoma patient outcome. Expression of trkA and trkC is linked to favorable prognosis, while amplification of the N-myc gene is strongly correlated to poor outcome. The role of trkA and trkC in neuroblastoma cell differentiation was studied using neuroblastoma cell lines constitutively expressing trkA or trkC. Stimulation of the trkA- and trkC-transfected cells with their cognate ligands resulted in differentiation of both cell clones, the differentiated trkC-transfected cells lacking important neuronal features present in the differentiated trkA-transfected cells. Signaling elicited by the two receptors was studied and differences described. The possible connection between expression of N-myc and trkB, another trk family member, was tested by examination of expression of these genes in a set of neuroblastomas and neuroblastoma cell lines. Results suggested high expression of N-myc per se to be insufficient to induce trkB expression. In other experiments, retinoic acid, an agent known to induce trkB expression was added to neuroblastoma cells in combination with the ligand of TrkB, brain-derived neurotrophic factor. Data from characterization of the resulting phenotype indicated that a sympathetic neuronal differentiation did not take place in these cells and alternative explanations were suggested. N-myc expression in the developing human sympathetic nervous system was studied using in situ hybridization and the role of N-myc in neuroblastoma cell was examined, utilizing non-N-myc-amplified neuroblastoma cells with constitutive N-myc overexpression as a model system. Overall, the capacity of these cells to differentitate morphologically in response to various differentiation protocols was retained, thus offering an explanation to the lack of correlation between N-myc expression and patient outcome in non-N-myc-amplified tumors.
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| 4. |
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| 5. |
- Vandesompele, J, et al.
(författare)
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ID2 expression in neuroblastoma does not correlate to MYCN levels and lacks prognostic value
- 2003
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 1476-5594 .- 0950-9232. ; 22:3, s. 456-460
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Tidskriftsartikel (refereegranskat)abstract
- The MYCN proto-oncogene is frequently amplified in a subgroup of highly aggressive neuroblastomas. The molecular mechanism(s) by which the overexpressed MYCN contributes to an aggressive tumor cell behavior is not well understood. Recently, it was reported that the ID2 gene is a direct target for the MYCN and MYC transcription factors, and that ID2 expression and MYCN amplification correlate positively in neuroblastoma. In addition, ID2 expression was proposed as a negative prognostic parameter. As these results are of potential clinical importance, but not in agreement with our own initial observations, the putative correlation between ID2 and MYC(N) expression in neuroblastoma cell lines and tumors was reinvestigated. We found no correlation between MYCN and ID2 expression in neuroblastoma cell lines or tumor specimens. However, we did find a significant positive correlation between MYC and ID2 expressions in both MYCN-amplified and single-copy tumor specimens, and in MYCN single-copy cell lines. As previously reported, we also found an inverse correlation between MYC and MYCN expressions. Importantly, we could not confirm the reported prognostic power of ID2-expression in neuroblastoma. These data, obtained in two independent laboratories, challenge the previously proposed ID2-MYCN relation.
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